<template>
    <div>
        <router-link 
            tag="div" 
            to="/" 
            class="header"
            v-show="showAbs"
        >
            <div class="header-abs">
                <div class="iconfont header-back">&#xe60a;</div>
            </div>
        </router-link>
        <div 
            class="header-fixed" 
            v-show="!showAbs"
            :style="opacityStyle"
        >
            <router-link to="/">
                <div class="iconfont header-fixed-back">&#xe60a;</div>
            </router-link>
                景点详情
        </div>
    </div>
</template>

<script>
export default {
    name: 'DetailHeader',
    data () {
        return {
            showAbs: true,
            opacityStyle: {
                opacity: 0
            }
        }
    },
    methods: {
        handleScroll () {
            const top = document.documentElement.scrollTop
            if (top > 60) {
                let opacity = top / 140
                opacity = opacity > 1 ? 1 : opacity
                this.opacityStyle = { opacity }
                this.showAbs = false
            }else {
                this.showAbs = true
            }
        }
    },
    activated () {
        window.addEventListener('scroll',this.handleScroll)
    },
    deactivated () {
        window.removeEventListener('scroll',this.handleScroll)
    }
}
</script>

<style lang="stylus" scoped>
     @import '~styles/varibles.styl'
    .header-abs
        position absolute
        left .2rem
        top .2rem
        width .8rem
        height .8rem       
        text-align center
        line-height .8rem
        border-radius .4rem
        background rgba(0,0,0,.8)
        .header-back 
         color #fff
         font-size .6rem
    .header-fixed
        z-index 2 
        position fixed
        top 0
        left 0
        right 0
        height $headerHeight
        line-height $headerHeight
        text-align center
        color #fff
        background $bgColor
        font-size .32rem
        .header-fixed-back 
            position absolute
            top 0
            left 0
            width .64rem
            text-align center
            font-size .5rem
            color #fff
            
</style>